RIR & RPE
RIR (Reps in Reserve) and RPE (Rate of Perceived Exertion) measure how hard a set was. HyperIron supports both and uses them to drive progression and track intensity.
RIR — Reps in Reserve
RIR is the number of reps you could have done but didn't. It directly measures proximity to failure.
| RIR | Meaning | How it feels |
|---|---|---|
| 4+ | 4 or more reps left | Warm-up territory |
| 3 | 3 reps left | Comfortable. Good for early mesocycle weeks. |
| 2 | 2 reps left | Working hard. Tough but manageable. |
| 1 | 1 rep left | Near failure. One more rep, maybe. |
| 0 | Failure | Could not complete another rep. |
How HyperIron uses RIR
Your program prescribes an RIR target for each week that ramps down over the mesocycle:
- First ~1/3 of weeks: RIR 3 — Build up, focus on technique
- Middle ~1/2 of weeks: RIR 2 — Moderate working effort
- Final weeks: RIR 1 (or 0) — Peak intensity
When you log a set, recording your actual RIR tells HyperIron whether the prescribed weight was appropriate. If you were supposed to be at RIR 2 but hit failure, the weight was too heavy.
RPE — Rate of Perceived Exertion
RPE rates effort on a 1–10 scale. In weightlifting, the modified Borg scale maps directly to RIR:
| RPE | RIR | Effort |
|---|---|---|
| 10 | 0 | Maximum — failure |
| 9.5 | 0–1 | Could maybe do one more |
| 9 | 1 | One rep left |
| 8.5 | 1–2 | One to two left |
| 8 | 2 | Two reps left |
| 7.5 | 2–3 | Two to three left |
| 7 | 3 | Three reps left |
| 6 | 4 | Easy effort |
Which to use?
They measure the same thing from different angles:
- RIR is more concrete — "I had 2 reps left" is a specific claim
- RPE is more intuitive for some — "that was an 8 out of 10"
HyperIron accepts both. When you enter one, the other is inferred automatically.
Getting better at estimating
Accurate RIR/RPE estimation improves with practice:
- Occasionally train to failure (safely, on machines or isolations) to calibrate what 0 RIR feels like
- Watch bar speed — noticeable slowing means RIR 2–3; grinding means RIR 0–1
- Don't stress precision — being within 1 RIR of your estimate is good enough
- Record something — rough estimates are far better than no data
Why it matters
RIR/RPE is optional but valuable:
- Better progression: Consistently higher effort than expected signals the weight ramp may be too aggressive
- Fatigue monitoring: A set that was RPE 7 last week but RPE 9 this week at the same weight reveals accumulated fatigue
- 1RM estimation: Combined with weight and reps, RPE can refine estimated one-rep max calculations
Even rough guesses make the system smarter. Your accuracy will improve over time.